At the moment I get phantastic speed rates with 2.4GHz, more than 10 times better than days before, nearly incredible, I reach 50Mbit/s with 2.4Ghz. Can this be true, but I tested different ways. If you are interested in the discussion please visit Archer C7 WDS Client: What is wrong with the configuration But I have problems to do tests with 5GHz, so I disabled it.
I suggest to stop this thread as long there is nothing new with beamforming. Maybe it is the beamforming of the R7800 which leads to my good values.